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Cell Cycle and Mitosis

Cell Cycle and Mitosis

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Cell Cycle and Mitosis

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  1. Cell Cycle and Mitosis

  2. Cell Cycle • Cell Cycle = the entire cycle of a cell from one division to the next • Interphase (G1, S, G2) = between cell divisions • M Phase (Mitosis and Cytokinesis) = cell division

  3. Interphase • Most of the time, a cell is in Interphase • G1 (Gap1) • Cell grows, copies organelles • Protein synthesis and all normal activities of cell (like cellular respiration) are carried out

  4. Interphase • S (Synthesis) • DNA is copied • Protein synthesis, cellular respiration occur • Cell continues to grow, copy organelles • G2 (Gap2) • Cell growth continues • Protein synthesis and cellular respiration occur

  5. M Phase • Mitosis = division of the nucleus • Cytokinesis = division of the rest of cytoplasm and its contents • Results in 2 identical daughter cells

  6. Duplicating Chromosomes • Before cell division can occur, all of the DNA must be copied in S phase • After duplication, you have 2 sister chromatids per chromosome

  7. Chromosome BEFORE duplication Chromosome AFTER duplication Chromosome after mitosis Sister Chromatids • Sister Chromatids = identical copies of a chromosome • Centromere = where sister chromatids are attached to one another

  8. Question… • Why do chromosomes duplicate? • To have a copy of DNA for each new daughter cell

  9. Haploid vs. Diploid • Diploid (2n) • 2 copies of each chromosome • All somatic cells are diploid (non-gametes) • Haploid (n) • 1 copy of each chromosome • Sperm and egg are haploid

  10. Mitosis vs. Meiosis • Mitosis • Results in 2 identical diploid daughter cells from the original diploid cell • Meiosis • Results in 4 nonidentical haploid cells from one original diploid cell

  11. Phases of Mitosis • Prophase • Prometaphase • Metaphase • Anaphase • Telophase “Pay Me AnyTime”

  12. Phases of Mitosis • Prophase (P) • Chromosomes begin to condense into chromatids • Mitotic spindle forming • Prometaphase • Chromosomes condensed & attached to spindle fibers, nuclear envelope in fragments

  13. Phases of Mitosis • Metaphase (M) • Chromosomes line up in the middle of the cell • Anaphase (A) • The spindle fibers pull the sister chromatids apart • Telophase (T) • Nuclear Envelope reforms

  14. Overview: Phases of Mitosis

  15. Cell Plate Cleavage Furrow Cytokinesis • Cytokinesis differs between Animal and Plant cells • Animal Cells – forms a cleavage furrow • Cells narrow and pinch off from each other • Plant Cells- forms a cell plate

  16. Binary Fission • Bacteria don’t go through mitosis • Why not? • No nucleus, just free floating DNA • Steps of Binary Fission • Cell grows in size • Copy DNA • Split cell into 2 new cells

  17. Cancer • Cancer is uncontrolled cell growth • Usually, the cell cycle is controlled by a variety of checkpoints and molecules • Cancer cells do not respond to these checkpoints  keep on dividing • Cancer cells no longer perform their normal functions, steal nutrients from other cells, crowd out other cells.